The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 15, 1994
Filed:
Jan. 13, 1993
Tsunetoshi Suzaki, Hiroshima, JP;
Tomoyoshi Iwao, Hiroshima, JP;
Teruo Tanaka, Tokyo, JP;
Toshiro Yamada, Osaka, JP;
Nisshin Steel Co., Ltd., Tokyo, JP;
Abstract
The high-temperature relaxation resistance of spring steel is improved by providing a specified composition of the steel, and subjecting that steel composition to a controlled heat treatment. The high-temperature relaxation resistance, which can not be estimated from the mechanical properties (e.g. strength and hardness) of steel materials at an ordinary temperature, is improved by these conditions which the inventors have found out from many experiments. Especially, the temper-softening resistance is enhanced by an increase of the Si content. The density of dislocation is lowered by providing fine carbides (MO.sub.2 C) serving as inhibitors for the migration of dislocation. These are precipitated by a controlled heat treatment without reducing hardness in the tempered state. Consequently, the obtained spring steel can be used operated in a high-temperature environment for a long time without a deterioration in its properties.